Transcutaneous magnetic bone conduction device

ABSTRACT

A bone conduction device for enhancing the hearing of a recipient, comprising: a sound input element configured to receive an acoustic sound signal; an electronics module configured generate an electrical signal representing the acoustic sound signal; a transducer configured to generate mechanical forces representing the electrical signal for deliver to the recipient&#39;s skull; one or more external components mechanically coupled to the transducer and configured to transfer the mechanical forces; and one or more implanted components magnetically coupled to the one or more external components and configured to receive the mechanical forces from the external components.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentApplication 61/041,185; filed Mar. 31, 2008, which is herebyincorporated by reference herein.

BACKGROUND

1. Field of the Invention

The present invention is generally directed to a bone conduction device,and more particularly, to a transcutaneous magnetic bone conductiondevice

2. Related Art

Hearing loss, which may be due to many different causes, is generally oftwo types, conductive or sensorineural. In many people who areprofoundly deaf, the reason for their deafness is sensorineural hearingloss. This type of hearing loss is due to absence, destruction, ordamage to the hairs that transduce acoustic signals into nerve impulsesin the cochlea. Various prosthetic hearing implants have been developedto provide individuals who suffer from sensorineural hearing loss withthe ability to perceive sound. One type of prosthetic implant, referredto as a cochlear implant, uses an electrode array implanted in thecochlea. More specifically, an electrical stimulus is provided via theelectrode array directly to the cochlea nerve, thereby inducing ahearing sensation in the implant recipient.

Conductive hearing loss occurs when the normal mechanical pathways,which conduct sound to hairs in the cochlea, are impeded. This problemmay arise from damage to the ossicular chain to ear canal. However,individuals who suffer from conductive hearing loss frequently stillhave some form of residual hearing because the hairs in the cochlea areoften undamaged. For this reason, individuals who suffer from conductivehearing loss are typically not candidates for a cochlear implant,because insertion of the electrode array into a cochlea may result inthe severe damage or destruction of the most of the hair cells withinthe cochlea.

Sufferers of conductive hearing loss typically receive an acoustichearing aid. Hearing aids receive ambient sound in the outer ear,amplify the sound, and direct the amplified sound into the ear canal.The amplified sound reaches the cochlea and causes motion of the cochleafluid, thereby stimulating the hairs in the cochlea.

An alternative to a normal air conduction aid is a bone conductionhearing aid which incorporates a hearing aid which drives a vibratorwhich is pushed against the skull via a mechanism. Such mechanismsinclude glasses and wire hoops. These devices are uncomfortable to wearand for some recipients are incapable of producing sufficient gain.

Unfortunately, hearing aids do not benefit all individuals who sufferfrom conductive hearing loss. For example, some individuals are prone tochronic inflammation or infection of the ear canal and cannot wearhearing aids. Other individuals have malformed or absent outer earand/or ear canals as a result of a birth defect, or as a result ofcommon medical conditions such as Treacher Collins syndrome or Microtia.Hearing aids are also typically unsuitable for individuals who sufferfrom single-sided deafness (i.e., total hearing loss only in one ear) orindividuals who suffer from mixed hearing losses (i.e., combinations ofsensorineural and conductive hearing loss).

Those individuals who cannot benefit from hearing aids may benefit fromhearing prostheses that are implanted into the skull bone. Such hearingprostheses direct vibrations into the bone, so that the vibrations areconducted into the cochlea and result in stimulation of the hairs in thecochlea. This type of prosthesis is typically referred to as a boneconduction device.

Bone conduction devices function by converting a received sound into amechanical vibration representative of the received sound. Thisvibration is then transferred to the bone structure of the skull,causing vibration of the recipient's skull and serves to stimulate thecochlea hairs, thereby inducing a hearing sensation in the recipient.

SUMMARY

According to one aspect of the present invention, there is provided abone conduction device for enhancing the hearing of a recipient,comprising: a sound input element configured to receive an acousticsound signal; an electronics module configured generate an electricalsignal representing the acoustic sound signal; a transducer configuredto generate mechanical forces representing the electrical signal fordeliver to the recipient's skull; one or more external componentsmechanically coupled to the transducer and configured to transfer themechanical forces; and one or more implanted components magneticallycoupled to the one or more external components and configured to receivethe mechanical forces from the external components.

According to another aspect of the present invention, there is provideda method for rehabilitating the hearing of a recipient with a boneconduction device having one or more external components and one or moreimplanted components, comprising: receiving an electrical signalrepresentative of an acoustic sound signal; generating mechanical forcesrepresentative of the received electrical signal; forming a magneticcoupling between the bone conduction device and the recipient's skull;and delivering the mechanical forces to the recipient's skull via themagnetic coupling.

According to yet another aspect of the present invention, there isprovided a bone conduction device for enhancing the hearing of arecipient having one or more external components and one or moreimplanted components, comprising: means for receiving an electricalsignal representative of an acoustic sound signal; means for generatingmechanical forces representative of the received electrical signal;means for forming a magnetic coupling between the bone conduction deviceand the recipient's skull; and means for delivering the mechanicalforces to the recipient's skull via the magnetic coupling.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the present invention are described hereinwith reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a transcutaneous bone conductionprovided to a recipient according to one embodiment of the presentinvention;

FIG. 2A is a high-level functional block diagram of a transcutaneousbone conduction device according to one embodiment of the presentinvention, such as the device of FIG. 1;

FIG. 2B is a detailed functional block diagram of the transcutaneousbone conduction device illustrated in FIG. 2A;

FIG. 3 is a flowchart illustrating the conversion of an input sound intoskull vibration in a transcutaneous bone conduction device according toone embodiment of the present invention;

FIG. 4 is a perspective view of a transcutaneous bone conduction deviceaccording to a further embodiment of the present invention;

FIG. 5A is a perspective side view of a transcutaneous bone conductiondevice according to another embodiment of the present invention;

FIG. 5B is an isometric view of the device shown in FIG. 5A;

FIG. 5C is a cross-sectional view of the device of FIG. 5B;

FIG. 6 is a perspective side view of a transcutaneous bone conductiondevice according to yet another embodiment of the present invention; and

FIG. 7 is a perspective side view of a transcutaneous bone conductiondevice according to a further embodiment of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention are generally directed to a boneconduction device for converting a received acoustic sound signal into amechanical force delivered transcutaneously via a recipient's skull tothe recipient's hearing organs. The bone conduction device includes asound input component, such as microphone, to receive the acoustic soundsignal, an electronics module configured to generate an electricalsignal representing the acoustic sound signal, and a piezoelectrictransducer to convert the electrical signal into a mechanical force fordelivery to the recipient's skull. In certain embodiments of the presentinvention, the transducer is connected to one or several magnets ormetal components which are magnetically coupled to magnets implantedbetween the recipient's bone and skin. In other embodiments of thepresent invention, one or several metal components, which are connectedto the transducer, are magnetically coupled to corresponding magnetsthat are implanted between the recipient's bone and skin. The magnets ormetal components connected to the transducer are connected such thatforce generated by the transducer is mechanically communicated to theconnected magnets or metal components, which in turn magneticallycommunicate the generate force or portions thereof to the implanted oneor several magnets or metal components. The piezoelectric transducer hasa piezoelectric element that deforms in response to application of theelectrical signal thereto. The transducer has an output stroke thatexceeds the deformation of the piezoelectric element.

The output stroke of the transducer (sometimes referred to herein as the“transducer stroke”) is utilized to generate a mechanical force that maybe provided to the recipient's skull. The sound perceived by a recipientis dependent, in part, upon the magnitude of mechanical force generatedby the transducer. In some bone conduction devices, the magnitude of themechanical force may be limited by the available transducer stroke.These limitations may cause distortion in the sound signal perceived bythe recipient or limit the population of recipient's that may benefitfrom the device. For example, in certain embodiments, limited transducerstroke results in insufficient gain to adequately represent a receivedacoustic sound signal for all individuals. This insufficient gain maycause a signal to be clipped or otherwise distorted.

As noted, the piezoelectric transducer comprises a piezoelectricelement. The piezoelectric element converts an electrical signal appliedthereto into a mechanical deformation (i.e. expansion or contraction) ofthe element. The amount of deformation of a piezoelectric element inresponse to an applied electrical signal depends on material propertiesof the element, orientation of the electric field with respect to thepolarization direction of the element, geometry of the element, etc.

The deformation of the piezoelectric element may also be characterizedby the free stroke and blocked force of the element. The free stroke ofa piezoelectric element refers to the magnitude of deformation inducedin the element when a given voltage is applied thereto. Blocked forcerefers to the force that must be applied to the piezoelectric element tostop all deformation at the given voltage. Generally speaking,piezoelectric elements have a high blocked force, but a low free stroke.In other words, when a voltage is applied to the element, the elementwill can output a high force, but will only a small stroke.

As noted, bone conduction devices generate a mechanical force that isdelivered to the skull, thereby causing motion of the cochlea fluid anda hearing perception by the recipient. In some piezoelectrictransducers, the maximum available transducer stroke is equivalent tothe free stroke of the piezoelectric element. As such, some boneconduction devices utilizing these types of piezoelectric transducerhave a limited transducer stroke and corresponding limits on themagnitude of the mechanical force that may be provided to the skull.

FIG. 1 is a perspective view of embodiments of a bone conduction device100 in which embodiments of the present invention may be advantageouslyimplemented. In a fully functional human hearing anatomy, outer ear 105comprises an auricle 105 and an ear canal 106. A sound wave or acousticpressure 107 is collected by auricle 105 and channeled into and throughear canal 106. Disposed across the distal end of ear canal 106 is atympanic membrane 104 which vibrates in response to acoustic wave 107.This vibration is coupled to oval window or fenestra ovalis 110 throughthree bones of middle ear 102, collectively referred to as the ossicles111 and comprising the malleus 112, the incus 113 and the stapes 114.Bones 112, 113 and 114 of middle ear 102 serve to filter and amplifyacoustic wave 107, causing oval window 110 to articulate, or vibrate.Such vibration sets up waves of fluid motion within cochlea 115. Suchfluid motion, in turn, activates tiny hair cells (not shown) that linethe inside of cochlea 115. Activation of the hair cells causesappropriate nerve impulses to be transferred through the spiral ganglioncells and auditory nerve 116 to the brain (not shown), where they areperceived as sound.

FIG. 1 also illustrates the positioning of bone conduction device 100relative to outer ear 101, middle ear 102 and inner ear 103 of arecipient of device 100. As shown, bone conduction device 100 may bepositioned behind outer ear 101 of the recipient.

In the embodiments illustrated in FIG. 1, bone conduction device 100comprises a housing 125 having a microphone (not shown) positionedtherein or thereon. Housing 125 is coupled to the body of the recipientvia coupling 140 and implanted magnet 162. As described below, boneconduction device 100 may comprise a sound processor, a transducer,transducer drive components and/or various other electroniccircuits/devices.

In accordance with embodiments of the present invention, an anchorsystem (not shown) may be implanted in the recipient. As describedbelow, the anchor system may be fixed to bone 136. In variousembodiments, the anchor system may be implanted under skin 132 withinmuscle 134 and/or fat 128. In certain embodiments, a coupling 140attaches device 100 to the anchor system.

A functional block diagram of one embodiment of bone conduction 100,referred to as bone conduction device 200, is shown in FIG. 2A. In theillustrated embodiment, a sound 207 is received by a sound input element202. In some embodiments, sound input element 202 is a microphoneconfigured to receive sound 207, and to convert sound 207 into anelectrical signal 222. As described below, in other embodiments sound207 may received by sound input element 202 as an electrical signal.

As shown in FIG. 2A, electrical signal 222 is output by sound inputelement 202 to an electronics module 204. Electronics module 204 isconfigured to convert electrical signal 222 into an adjusted electricalsignal 224. As described below in more detail, electronics module 204may include a sound processor, control electronics, transducer drivecomponents, and a variety of other elements.

As shown in FIG. 2A, transducer 206 receives adjusted electrical signal224 and generates a mechanical output force that is delivered to theskull of the recipient via coupling 140, shown in FIG. 2A as anchorsystem 208, that is coupled to bone conduction device 200. Delivery ofthis output force causes one or more of motion or vibration of therecipient's skull, thereby activating the hair cells in the cochlea viacochlea fluid motion.

FIG. 2A also illustrates a power module 210. Power module 210 provideselectrical power to one or more components of bone conduction device200. For ease of illustration, power module 210 has been shown connectedonly to interface module 212 and electronics module 204. However, itshould be appreciated that power module 210 may be used to supply powerto any electrically powered circuits/components of bone conductiondevice 200.

Bone conduction device 200 further includes an interface module 212 thatallows the recipient to interact with device 200. For example, interfacemodule 212 may allow the recipient to adjust the volume, alter thespeech processing strategies, power on/off the device, etc. Interfacemodule 212 communicates with electronics module 204 via signal line 228.

In the embodiment illustrated in FIG. 2A, sound pickup device 202,electronics module 204, transducer 206, power module 210 and interfacemodule 212 have all been shown as integrated in a single housing,referred to as housing 225. However, it should be appreciated that incertain embodiments of the present invention, one or more of theillustrated components may be housed in separate or different housings.Similarly, it should also be appreciated that in such embodiments,direct connections between the various modules and devices are notnecessary and that the components may communicate, for example, viawireless connections.

In embodiments of the present invention, transducer 206 may be one ofmany types and configurations of transducers, now known or laterdeveloped. In one embodiment of the present invention, transducer 206may comprise a piezoelectric element which is configured to deform inresponse to the application of electrical signal 224. Piezoelectricelements that may be used in embodiments of the present invention maycomprise, for example, piezoelectric crystals, piezoelectric ceramics,or some other material exhibiting a deformation in response to anapplied electrical signal. Exemplary piezoelectric crystals includequartz (SiO2), Berlinite (AlPO4), Gallium orthophosphate (GaPO4) andTourmaline. Exemplary piezoelectric ceramics include barium titanate(BaTiO30), lead zirconium titanate (PZT), or zirconium (Zr).

Some piezoelectric materials, such as lead zircoium titanate and PZT,are polarized materials. When an electric field is applied across thesematerials, the polarized molecules align themselves with the electricfield, resulting in induced dipoles within the molecular or crystalstructure of the material. This alignment of molecules causes thedeformation of the material.

In other embodiments of the present invention, other types oftransducers may be used. For example, various motors configured tooperate in response to electrical signal 224 may be used.

In one embodiment of the present invention, transducer 206 generates anoutput force that causes movement of the cochlea fluid so that a soundmay be perceived by the recipient. The output force may result inmechanical vibration of the recipient's skull, or in physical movementof the skull about the neck of the recipient. As noted above, in certainembodiments, bone conduction device 300 delivers the output force to theskull of the recipient via an anchor system 208. In one embodiment ofthe present invention, anchor system 208 comprises one or more externalmagnets 260 which magnetically couples to one or more implanted magnets262, as illustrated in FIG. 2B. In the embodiment illustrated in FIG.2A, external magnets 260 are configured to be attached to housing 225.As such, in this embodiment, vibration from transducer 206 is providedto external magnets 260 through housing 225.

In certain embodiments of the present invention, electronics module 204includes a printed circuit board (PCB) to electrically connect andmechanically support the components of electronics module 204. Soundinput element 202 may comprise one or more microphones (not shown) andis attached to the PCB.

FIG. 2B provides a more detailed view of bone conduction device 200 ofFIG. 2A. In the illustrated embodiment, electronics module 204 comprisesa sound processor 240, transducer drive components 242 and controlelectronics 246. As explained above, in certain embodiments sound inputelement 202 comprises a microphone configured to convert a receivedacoustic signal into electrical signal 222. In other embodiments, asdetailed below, sound input element 202 receives sound 207 as anelectrical signal.

In embodiments of the present invention, electrical signal 222 is outputfrom sound input element 202 to sound processor 240. Sound processor 240uses one or more of a plurality of techniques to selectively process,amplify and/or filter electrical signal 222 to generate a processedsignal 224A. In certain embodiments, sound processor 240 may comprisesubstantially the same sound processor as is used in an air conductionhearing aid. In further embodiments, sound processor 240 comprises adigital signal processor.

Processed signal 224A is provided to transducer drive components 242.Transducer drive components 242 output a drive signal 224B, totransducer 206. Based on drive signal 224B, transducer 206 provides theoutput force to the skull of the recipient.

For ease of description the electrical signal supplied by transducerdrive components 242 to transducer 206 has been referred to as drivesignal 224B. However, it should be appreciated that processed signal224B may comprise an unmodified version of processed signal 224A.

As noted above, transducer 206 generates an output force to the skull ofthe recipient via anchor system 208. As shown in FIG. 2B, in oneembodiment of the present invention, anchor system 208 comprises anexternal magnet 260 which magnetically couples to an implanted magnet262. External magnet 260 may be attached to one or more of transducer206 or housing 225. For example, in certain embodiments, external magnet260 is attached to transducer 206 and vibration is received directlytherefrom. In other embodiments, external magnet 260 is attached tohousing 225 and vibration is applied from transducer 206 through housing225 to external magnet 260. According to one embodiment of the presentinvention in which coupling 140 comprises external magnet 260, thevibration received by external magnet 260 from transducer 206 causesexternal magnet 260 to vibrate. Since, according to this embodiment ofthe present invention, external magnet 260 is magnetically coupled toimplanted magnet 262, the magnetic forces coupling external magnet 260and implanted magnet 262 vibrates accordingly. The vibration,communicated from external magnet 260 to implanted magnet 262magnetically, is then transferred from implanted magnet 262 to therecipient's bone 136.

As noted above, a recipient may control various functions of the devicevia interface module 212. Interface module 212 includes one or morecomponents that allow the recipient to provide inputs to, or receiveinformation from, elements of bone conduction device 200.

As shown, control electronics 246 may be connected to one or more ofinterface module 212, sound pickup device 202, sound processor 240and/or transducer drive components 242. In embodiments of the presentinvention, based on inputs received at interface module 212, controlelectronics 246 may provide instructions to, or request informationfrom, other components of bone conduction device 200. In certainembodiments, in the absence of user inputs, control electronics 246control the operation of bone conduction device 200.

FIG. 3 illustrates the conversion of an input acoustic sound signal intoa mechanical force for delivery to the recipient's skull in accordancewith embodiments of bone conduction device 200. At block 302, boneconduction device 200 receives an acoustic sound signal. In certainembodiments, the acoustic sound signal is received via microphones. Inother embodiments, the input sound is received via an electrical input.In still other embodiments, a telecoil integrated in, or connected to,bone conduction device 200 may be used to receive the acoustic soundsignal.

At block 304, the acoustic sound signal received by bone conductiondevice 200 is processed by the speech processor in electronics module204. As explained above, the speech processor may be similar to speechprocessors used in acoustic hearing aids. In such embodiments, speechprocessor may selectively amplify, filter and/or modify acoustic soundsignal. For example, speech processor may be used to eliminatebackground or other unwanted noise signals received by bone conductiondevice 200.

At block 306, the processed sound signal is provided to transducer 206as an electrical signal. At block 308, transducer 206 converts theelectrical signal into a mechanical force configured to be delivered tothe recipient's skull via anchor system 208 so as to illicit a hearingperception of the acoustic sound signal.

FIG. 4 illustrates one embodiment of the present invention in whichanchor system 208 comprises a single external magnet 408. Externalmagnet 408 magnetically couples with implanted magnet 462 and deliversthe mechanical force 470 from transducer module 406 to the recipient'sskull 136. As will be appreciated by persons having skill in the art,implanted magnet 462 is attached to recipient's skull 136 in a varietyof ways. For example, implanted magnet 462 may be bonded to recipient'sskull 136 using one or more adhesive compounds. Also, for example,implanted magnet 462 may be attached by bonding or other means to anosseointegrative mesh or other structure which is configured tointegrate with the recipient's skull bone over a period of time.Furthermore, in other embodiments of the present invention, implantedmagnet 462 may be sutured into place, where the suture provides aninterference pressure upon implanted magnet 462 against the recipient'sskull. Alternatively, implanted magnet 462 may have structural featureswhich are designed or may additionally be used by a suture to holdimplanted magnet 462 against the recipient's skull. It is also to beunderstood that as implanted magnet 462 is positioned between therecipient's tissue 132, 128, 134 and the recipient's skull 136, thecompression between the recipient's tissue and skull may be the primarymechanism used to keep implanted magnet 162 is a fixed position.

Also, it is to be understood that in certain embodiments of the presentinvention, recipient's skull may be modified (not shown) to create a bedsized according to the circumferential dimensions of implanted magnet462, where the bed has a depth to at least partially or completelyreceive the full thickness of implanted magnet 462. Additionally, aswill be described later in conjunction with the embodiment illustratedin FIG. 7, implanted magnet 462 may be bonded or otherwise attached to aplate which is itself attached to recipient's bone using, for example,screws which enter recipient's bone to fix the plate to the bone.Although FIG. 4 illustrates speech processor 404 as being in a separatehousing from transducer 406, it is to be understood that transducer 406and speech processor 404 may be housed in a single housing such ashousing 125 as illustrated in FIG. 1.

In FIG. 4, mechanical force 470 is produced by transducer 406 as a forcethat is directed in a perpendicular manner with respect to recipient'sskull 136. However, it is to be understood that in other embodiments ofthe present invention, mechanical force 470 may be produced bytransducer 406 in a non-perpendicular manner, for example, parallel tothe surface of recipient's bone 136. It should be understood that thevarious directions or projections of mechanical forces generated anddelivered via the magnetic coupling described above to recipient's bone136 are considered a part of the present invention.

FIG. 5A illustrates another embodiment of the bone conduction device 100of FIG. 1, referred to as bone conduction device 500. In thisembodiment, two external magnets 508A and 508B (referred to collectivelyas external magnets 508) are attached to housing 525. In this embodimentof the present invention, the transducer module (not shown) in housing525 generates a mechanical force which is transferred via housing 525 toexternal magnets 508. External magnets 508 are magnetically coupled toimplanted magnets 562A and 562B (referred to collectively as implantedmagnets 562). As illustrated in FIG. 5A, perpendicular force 570A istransmitted from external magnet 508A to implanted magnet 562A andperpendicular force 570B is transmitted from external magnet 508B toimplanted magnet 562B. Implanted magnets 562 in turn transmit thereceived perpendicular force to recipient's skull 136 in a manner asdescribed above. Implanted magnets 562 may be attached to or bonded torecipient's skull 136 as described above in conjunction with FIG. 4.

Although FIGS. 5A, 5B and 5C depict bone conduction device 500 as havingtwo external and implanted magnets 508, 562, it is to be understood thatdevice 500 may comprise a larger number or configuration of magnets.Furthermore, it is to be understood that implanted magnets 562 may beattached to one another such that only a subset of implanted magnets 562may be fixed to recipient's skull 136 in such a way that the fixedimplant magnet provides fixation for the other implanted magnets 562.Similarly, it is to be understood that in other embodiments of thepresent invention, external magnets 508 may be attached or otherwiseconnected to each other, for example on a shared plate or base which isitself attached or coupled to transducer 525.

FIG. 5B shows a perspective view of one embodiment of the presentinvention, demonstrating one configuration in which external magnets 508are arranged to magnetically couple to implanted magnets (not shown). Across-section of FIG. 5B is shown as FIG. 5C, which also illustratesexternal magnets 508 and housing 525. In the embodiment illustrated inFIGS. 5B and 5C, the various other components of bone conduction device500 is contained in housing 525, including the transducer whichtransmits mechanical force to housing 525 such that external magnets 508receives and transmits that force to implant magnets (not shown).

FIG. 6 illustrates another embodiment of the bone conduction device 500of FIG. 5A, referred to as bone conduction device 600. As in theembodiment illustrated in FIG. 5A, in this embodiment, two externalmagnets 608A and 608B (referred to collectively as external magnets 608)are attached to housing 625. In this embodiment of the presentinvention, the transducer module (not shown) in housing 625 generates amechanical force substantially parallel to the surface of recipient'sskull 136 which is transferred via housing 625 to external magnets 608.External magnets 608 are magnetically coupled to implanted magnets 662Aand 662B (referred to collectively as implanted magnets 662). Asillustrated in FIG. 6, parallel force 670A is transmitted from externalmagnet 608A to implanted magnet 662A, and parallel force 670B istransmitted from external magnet 608B to implanted magnet 662B.Implanted magnets 662 in turn transmit the received parallel force torecipient's skull 136 in a manner as described above.

As noted previously, according to embodiments of the present invention,the implanted magnets may be fixed to the recipient's skull in variousways. For example, in the embodiment illustrated in FIG. 7, boneconduction device 700 comprises housing 725 comprising a transducer (notshown) among other device components. External magnets 708A and 708B(collectively referred to as external magnets 708) are attached tohousing 725 and receive the mechanical forces generated by transducervia the surface of housing 725. External magnets 708 are magneticallycoupled to implanted magnets 762A and 672B collectively referred to asimplanted magnets 762) and transmit the mechanical forces received toimplant magnets 762 as magnetic forces 770A and 770B (collectivelyreferred to as magnetic forces 770). In the illustrated embodiment, theforces generated by the transducer (not shown) in housing 725 aredirected in parallel with respect to the surface of the recipient'sskull 136. Therefore, external magnets 708 are caused to correspondinglymove in parallel to the recipient's skull, which results in the magneticforces 770 moving in parallel with respect to recipient's skull 136.

Implanted magnets 762 are attached to plate 780, which is fixed torecipient's skull 136 using fixation screws 782A and 782B (collectivelyreferred to as screws 782). In the embodiment illustrated in FIG. 7,even though magnetic forces 770 are directed only to implanted magnets762 and not to plate 780, because implanted magnets 762 are attached toplate 780, magnetic forces 770 are transferred from implanted magnets762 to plate 780 and then to recipient's skull 136.

Although embodiments of the present invention have been described abovewhere the one or more external magnets couple to one or more implantedmagnets, it is to be understood that an iron-based metal may be used inplace of either the external or implanted magnets so long as themagnetic coupling between the magnet and metal is of sufficient strengthto enable adequate transfer of the mechanical forces generated by thetransducer.

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only, and not limitation. It will be apparent to persons skilledin the relevant art that various changes in form and detail can be madetherein without departing from the spirit and scope of the invention.Thus, the breadth and scope of the present invention should not belimited by any of the above-described exemplary embodiments, but shouldbe defined only in accordance with the following claims and theirequivalents. All patents and publications discussed herein areincorporated in their entirety by reference thereto.

1. A bone conduction device for enhancing the hearing of a recipient,comprising: a sound input element configured to receive an acousticsound signal; an electronics module configured generate an electricalsignal representing said acoustic sound signal; a transducer configuredto generate mechanical forces representing said electrical signal fordeliver to the recipient's skull; one or more external componentsmechanically coupled to said transducer and configured to transfer saidmechanical forces; and one or more implanted components magneticallycoupled to said one or more external components and configured toreceive said mechanical forces from said external components.
 2. Thedevice of claim 1, wherein said external components and said implantedcomponents each comprise magnets.
 3. The device of claim 1, wherein saidonly one of said external components and said implanted componentscomprise magnets.
 4. The device of claim 1, wherein each of said one ormore implanted component is configured to be inserted into therecipient's skull in one or more corresponding beds formed in the skulland configured to accommodate said implanted components.
 5. The deviceof claim 1, wherein said one or more implanted components are fixedlyattached to the recipient's skull.
 6. The device of claim 5, whereinsaid one or more implanted components are bonded to the recipient'sskull.
 7. The device of claim 5, wherein said one or more implantedcomponents are attached to one or more plates fixed to the recipient'sskull.
 8. The device of claim 5, wherein said one or more implantedcomponents are fixed by one or more screws to the recipient's skull. 9.The device of claim 5, wherein said one or more implanted components arefixed to an osseointegrative mesh which is configured to integrate withthe recipient's skull.
 10. The device of claim 1, wherein saidmechanical force is generated by said transducer in parallel withrespect to the surface of the recipient's skull.
 11. The device of claim1, wherein said mechanical force is generated by said transducerperpendicular to the surface of the recipient's skull.
 12. A method forrehabilitating the hearing of a recipient with a bone conduction devicehaving one or more external components and one or more implantedcomponents, comprising: receiving an electrical signal representative ofan acoustic sound signal; generating mechanical forces representative ofthe received electrical signal; forming a magnetic coupling between thebone conduction device and the recipient's skull; and delivering saidmechanical forces to the recipient's skull via the magnetic coupling.13. The method of claim 12, wherein the magnetic coupling is formedusing one or more implanted magnets.
 14. The method of claim 12, whereinthe magnetic coupling is formed using one or more external magnets. 15.The method of claim 12, further comprising: forming a bed in therecipient's skull in which the implanted components are configured to bepositioned.
 16. The method of claim 12, further comprising: attachingthe one or more implanted components to the recipient's skull.
 17. Themethod of claim 16, wherein said one or more implanted components areattached by bonding to the recipient's skull.
 18. The method of claim16, wherein said one or more implanted components are attached to one ormore plates fixed to the recipient's skull.
 19. The method of claim 16,wherein said one or more implanted components are attached by one ormore screws to the recipient's skull.
 20. The method of claim 16,wherein said one or more implanted components are fixed to anosseointegrative mesh which is configured to attach to recipient's skullby osseointegration over time.
 21. A bone conduction device forenhancing the hearing of a recipient having one or more externalcomponents and one or more implanted components, comprising: means forreceiving an electrical signal representative of an acoustic soundsignal; means for generating mechanical forces representative of thereceived electrical signal; means for forming a magnetic couplingbetween the bone conduction device and the recipient's skull; and meansfor delivering said mechanical forces to the recipient's skull via themagnetic coupling.
 22. The method of claim 21, further comprising: meansfor receiving the implanted components in the recipient's skull.
 23. Themethod of claim 21, further comprising: means for attaching the one ormore implanted components to the recipient's skull.